Pulpstone and filler for the same



April 27, 1937. T. LARSSON PULPSTONE AND FILLER FOR THE S AME Filed Dec. 12, 1935 Patented Apr. 27, 1937 UNlTED STATES PATENT OFFICE PULPSTONE AND FILLER FOR- THE SAME Application December 12, 1935, Serial No. 54,110

1 Claim.

The invention relates to segmental grinding wheels and with regard to its more specific features to the artificial pulpstone type of grinding Wheel comprising a plurality of segments joined 5 together, with a filling medium filling the radial interstices between the segments.

One object of the invention is to provide an improved construction of grinding wheel segments and filler. Another object of the invention is to provide a structure for the segments and a filler which shall be deformable under conditions of overload. Another object of the invention is to provide a pulpstone structure capable of resisting abnormal changes of temperature.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts, and in the several steps and relation and order of each of said steps to one or more of the others thereof, all as will be illustratively described herein, and the scope of the application of which will be indicated in the following claim.

In the accompanying drawing in which is shown one of various possible embodiments of the mechanical features of this invention,

Fig. l is a fragmentary cross sectional view in a plane perpendicular to the axis of a segmental pulpstone, and

Fig. 2 is a fragmentary isometric View of the pulpstone.

As conducive to a clearer understanding of the present invention, it is noted that pulpstones are usually embodied in very large wheels, the natural sandstone having been used previously. Because of many features which need not be specifically mentioned herein, an artificial pulpstone comprising a plurality of segments each consisting of abrasive grains and bond, and the segments being secured together, is at present preferred. Pulpstones are used for the grinding of logs in the manufacture of paper, and generate a considerable amount of heat. Furthermore, it occasionally happens that the usual supply of water runs out and in that event the pulpstone becomes very much overheated. The same stone, however, may at some time be cooled to temperatures met with outdoors in the winter in the northern temperate or even in the arctic zones.

Considering now the illustrative embodiment of the invention, I provide a segmental grinding 55 myself and Beth No. 1,736,161 dated November 19, 1929. Referring now to Fig. 1, I provide a drum I having abrasive segments 2, 2 mounted thereon. The drum I, which is suitably mounted for rotation, has a cylindrical outer surface 3 and several rows of abrasive segments arefastened thereon with their inner peripheral surfaces fitting the drum and with their outer surfaces forming a substantially cylindrical peripheral grinding surface 5. The rows of abrasive segments are so shaped as to fit together along radial or other planes as shown, for example, in the patent to Greenwood No. 1,469,723 dated October 2, 1923, and they are clamped in position on the drum by means of wedge blocks 6, each of which is adjustably fastened to the drum by means of bolts 1. between the segments in grooves in the sides of adjacent segments, the wedge blocks having bevelled faces and the grooves being correspondingly shaped so that tightening the bolts to draw the blocks inwardly forces the segments into a tight fit on the drum.

Considering now the preferred embodiment of the present invention, I provide a series of parallel grooves 10 along one entire side of each block 2 which is at an angle to a plane normal to the axis of the entire pulpstone. These grooves I are spaced from each other by lands or ridges i I, and the lands or ridges l I are relatively narrow as compared with the width of the grooves I0. Preferably before assembling the abrasive segments 2 onto the drum I, I fill all of the grooves l0 with some water removable material, for example clay. When the segments have been mounted upon the drum l and secured in place I pour Babbitt metal I3 or the like into the remaining spaces between abrasive segments, thus forming Babbitt fillers l3 as shown in the draw- The construction of the invention operates to safeguard the wheel as follows: When, in the grinding of pulp or otherwise overheating occurs, as such overheating usually takes place at the periphery of the wheel, the segments 2 expand against each other reacting against the filler material l3. This filler material I3 is deformable for the reason that the pressure is taken by the narrow lands 1 I rather than by the entire surface of the segments. Accordingly, under such conditions of operation, the Babbitt metal 13 deforms and injury to the pulpstone is prevented.

The water removable material l2 may wash out during grinding, and when the stone has once been overheated there may be a gap between the material l3 and the next adjacent grooves Hi The wedge blocks are located v and lands H. However, such spaces are filled with pulp or other matter and the voids do not prevent successful operation of the wheel. It is preferable to rotate the wheel in the direction of the arrows so that the Babbitt metal #3 or the like will be forced against the plane surfaces of the segments.

It will thus be seen that there has been provided by this invention a method and an apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As various possible embodiments might be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim:-

A segmental grinding wheel comprising a center portion, a series of abrasive segments whose angular displacement is nearly but not quite great enough to extend all the way around the center portion, thus providing for crevices between the segments, means holding the segments to the center portion to leave crevices between adjacent segments, a plurality of ridges integral with and extending from a segment at each crevice, and a filler in each crevice flush with the plane of one segment and contacting the ridges on the other side of the crevice and terminating substantially at the plane of the ridges, whereby the filler will be compressed by the ridges in the event of expansion of the wheel.

THURE LARSSON. 

